diff options
author | Jeff Layton <jlayton@kernel.org> | 2023-01-05 22:55:56 +0300 |
---|---|---|
committer | Chuck Lever <chuck.lever@oracle.com> | 2023-01-06 21:17:06 +0300 |
commit | 0b3a551fa58b4da941efeb209b3770868e2eddd7 (patch) | |
tree | fd441dccde73209161fefb00387292036b7b1faf /fs/nfsd/filecache.c | |
parent | cad853374d85fe678d721512cecfabd7636e51f3 (diff) | |
download | linux-0b3a551fa58b4da941efeb209b3770868e2eddd7.tar.xz |
nfsd: fix handling of cached open files in nfsd4_open codepath
Commit fb70bf124b05 ("NFSD: Instantiate a struct file when creating a
regular NFSv4 file") added the ability to cache an open fd over a
compound. There are a couple of problems with the way this currently
works:
It's racy, as a newly-created nfsd_file can end up with its PENDING bit
cleared while the nf is hashed, and the nf_file pointer is still zeroed
out. Other tasks can find it in this state and they expect to see a
valid nf_file, and can oops if nf_file is NULL.
Also, there is no guarantee that we'll end up creating a new nfsd_file
if one is already in the hash. If an extant entry is in the hash with a
valid nf_file, nfs4_get_vfs_file will clobber its nf_file pointer with
the value of op_file and the old nf_file will leak.
Fix both issues by making a new nfsd_file_acquirei_opened variant that
takes an optional file pointer. If one is present when this is called,
we'll take a new reference to it instead of trying to open the file. If
the nfsd_file already has a valid nf_file, we'll just ignore the
optional file and pass the nfsd_file back as-is.
Also rework the tracepoints a bit to allow for an "opened" variant and
don't try to avoid counting acquisitions in the case where we already
have a cached open file.
Fixes: fb70bf124b05 ("NFSD: Instantiate a struct file when creating a regular NFSv4 file")
Cc: Trond Myklebust <trondmy@hammerspace.com>
Reported-by: Stanislav Saner <ssaner@redhat.com>
Reported-and-Tested-by: Ruben Vestergaard <rubenv@drcmr.dk>
Reported-and-Tested-by: Torkil Svensgaard <torkil@drcmr.dk>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Diffstat (limited to 'fs/nfsd/filecache.c')
-rw-r--r-- | fs/nfsd/filecache.c | 40 |
1 files changed, 22 insertions, 18 deletions
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c index 45b2c9e3f636..0ef070349014 100644 --- a/fs/nfsd/filecache.c +++ b/fs/nfsd/filecache.c @@ -1071,8 +1071,8 @@ nfsd_file_is_cached(struct inode *inode) static __be32 nfsd_file_do_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, - unsigned int may_flags, struct nfsd_file **pnf, - bool open, bool want_gc) + unsigned int may_flags, struct file *file, + struct nfsd_file **pnf, bool want_gc) { struct nfsd_file_lookup_key key = { .type = NFSD_FILE_KEY_FULL, @@ -1147,8 +1147,7 @@ wait_for_construction: status = nfserrno(nfsd_open_break_lease(file_inode(nf->nf_file), may_flags)); out: if (status == nfs_ok) { - if (open) - this_cpu_inc(nfsd_file_acquisitions); + this_cpu_inc(nfsd_file_acquisitions); *pnf = nf; } else { if (refcount_dec_and_test(&nf->nf_ref)) @@ -1158,20 +1157,23 @@ out: out_status: put_cred(key.cred); - if (open) - trace_nfsd_file_acquire(rqstp, key.inode, may_flags, nf, status); + trace_nfsd_file_acquire(rqstp, key.inode, may_flags, nf, status); return status; open_file: trace_nfsd_file_alloc(nf); nf->nf_mark = nfsd_file_mark_find_or_create(nf, key.inode); if (nf->nf_mark) { - if (open) { + if (file) { + get_file(file); + nf->nf_file = file; + status = nfs_ok; + trace_nfsd_file_opened(nf, status); + } else { status = nfsd_open_verified(rqstp, fhp, may_flags, &nf->nf_file); trace_nfsd_file_open(nf, status); - } else - status = nfs_ok; + } } else status = nfserr_jukebox; /* @@ -1207,7 +1209,7 @@ __be32 nfsd_file_acquire_gc(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **pnf) { - return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true, true); + return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, true); } /** @@ -1228,28 +1230,30 @@ __be32 nfsd_file_acquire(struct svc_rqst *rqstp, struct svc_fh *fhp, unsigned int may_flags, struct nfsd_file **pnf) { - return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, true, false); + return nfsd_file_do_acquire(rqstp, fhp, may_flags, NULL, pnf, false); } /** - * nfsd_file_create - Get a struct nfsd_file, do not open + * nfsd_file_acquire_opened - Get a struct nfsd_file using existing open file * @rqstp: the RPC transaction being executed * @fhp: the NFS filehandle of the file just created * @may_flags: NFSD_MAY_ settings for the file + * @file: cached, already-open file (may be NULL) * @pnf: OUT: new or found "struct nfsd_file" object * - * The nfsd_file_object returned by this API is reference-counted - * but not garbage-collected. The object is released immediately - * one RCU grace period after the final nfsd_file_put(). + * Acquire a nfsd_file object that is not GC'ed. If one doesn't already exist, + * and @file is non-NULL, use it to instantiate a new nfsd_file instead of + * opening a new one. * * Returns nfs_ok and sets @pnf on success; otherwise an nfsstat in * network byte order is returned. */ __be32 -nfsd_file_create(struct svc_rqst *rqstp, struct svc_fh *fhp, - unsigned int may_flags, struct nfsd_file **pnf) +nfsd_file_acquire_opened(struct svc_rqst *rqstp, struct svc_fh *fhp, + unsigned int may_flags, struct file *file, + struct nfsd_file **pnf) { - return nfsd_file_do_acquire(rqstp, fhp, may_flags, pnf, false, false); + return nfsd_file_do_acquire(rqstp, fhp, may_flags, file, pnf, false); } /* |